Environmental Engineering Reference
In-Depth Information
Table 4.23 In-vehicle communications networks
Network class
Speed
Application
Class A: LIN, TTP/A
<
10 kb/s
Customer amenities: power seats, windows,
mirrors, trunk release etc.
Class B: J1850,
ISO 9141-2
10 kb/s
!
125 kb/s
Information transfer: cabin climate control,
dash board instrumentation, convenience
features etc.
Class C: CAN, J1039
125 kb/s
!
12 Mb/s
Real time control: powertrain and vehicle
dynamics
Class D: MOST,
FlexRay
>
1 Mb/s
Multimedia and safety critical applications:
x-by-wire, digital TV, Internet
4.6.2 Power and data networks
Modern vehicles, and particularly hybrid vehicles, are evolving to a four layer
power and data communications architecture. The four layer model is based on
broad classes of functionality, data transmission speed and data protocols asso-
ciated with broad classes of speeds.
The four layer model includes power distribution in an open architecture sense
of generation, storage and distribution systems; safety and mobility including air-
bag deployment control to powertrain and x-by-wire controls; body layer including
interior and exterior lighting, customer amenities and instrumentation; infotainment
layer including high end audio products, TV, wireless phone, voice actuated sys-
tems, navigation aides and other additions in a scaleable and flexible architecture.
In-vehicle architectures, besides being open, are hierarchical by design. A hier-
archical architecture adheres to strict protocols of top down command flow and
upward flow of data. Lateral data flow is allowed, but lateral command flow is pro-
hibited. This is the architecture of choice for hybrid propulsion in which a high level
vehicle system controller coordinates its various subsystems as shown in Figure 4.49.
Vehicle system
controller
Power and communications (PDA)
ISG subsystem
belt or crankshaft
Steering
electric assist
Steering actuator
Brakes
regen brake sys
42 V battery
primary storage
Other 42 V
loads
Brake actuators
ISG
torque
SOC, SOH,Vsys
Continuous,
scheduled,
selectable
Engine
Transmission
ETC, fan,
water pump
Gear sel, LUC clutch
oil pump
UC
UC
UC
ECU
ECU
Mtr
ECU
HCU
Brake
pedal
Accel
pedal
Mtr
Steering
wheel
Throttle
body
Figure 4.49 Hierarchical power and data architecture
